Fuel system with direct connection between fuel pump, jet pump, and fuel filter

ABSTRACT

Fuel system comprising a fuel tank, a main fuel supply pump ( 2 ), a fuel filter ( 4 ) comprising a housing and a filter element, a reservoir ( 10 ) within the fuel tank and a jet pump ( 3 ) for filling said reservoir, wherein a one piece connector ( 1 ) directly connects the main fuel supply pump ( 2 ), the fuel filter ( 4 ) and the jet pump ( 3 ).

TITLE OF THE INVENTION

This application claims priority to U.S. provisional application60/661,405, filed on Mar. 14, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of fuel systems that includea fuel pump, a jet pump and a fuel filter.

2. Discussion of the Background

To date, the fuel delivery modules (FDM) require a substantial reservoircapacity to provide enough reserve fuel for low fuel considerations.

It is namely so that in certain circumstances, for example, when thevolume of fuel contained in the fuel tank of an automotive vehicle fallsbelow a certain minimum level and this vehicle travels through aprolonged curve, uphill or downhill, or if it is otherwise subjected tosudden and pronounced changes in speed, direction, etc., the fuel couldbe displaced to one side of the tank to such an extent that the inletend of the dip tube, which forms part of the fuel-intake tubing, is atleast temporarily no longer submerged in the fuel. Under suchconditions, the dip tube sucks out air instead of fuel, therebyproducing an interruption in the feed fuel flow that impedes the properoperation of the internal-combustion engine.

In order to avoid such problems, most fuel tanks include a reservoiri.e. a subtank intended to trap fuel and act as a reserve.

The use of a jet pump to fill a fuel reservoir within a fuel tank is acommon technology. Typically, there is a separate pressurized fuel linefrom the outlet of the fuel pump or positive pressure from a connectionto the pumping element or the return fuel from a fuel pressure regulatorwhich connects to and supplies a jet pump which fills the reservoir toprovide a reserve fuel supply for the fuel pump for low fuel conditionssuch as:

-   -   Hard acceleration/deceleration    -   Extended turns like a “clover leaf” on a highway access or        egress.    -   Ascending or descending grades, (i.e. Sandia Pass in New Mexico)

This Fuel line is in addition to the supply line to the engine andrequires additional clamps and fittings to complete the circuit.Packaging the jet pump components presents complications in terms oflocating the features without adding complexity to the reservoir and/orfuel pressure supply line. These additional components also add to thepotential failure modes that must be considered and addressed withcorrective actions in the design of the fuel delivery module.

Additionally, static electricity can build up within the pump, filtermedia and flow path to the point where the potential is high enough tocause an electrical discharge to the nearest ground point. This cancause electrical noise or, in the worst case, a thermal event inside thefuel tank. To solve that problem, a wire is often used to connect thenegative (ground) terminal of the pump or the negative ground terminalof the fuel level sender and the conductive plastic filter housing. Anystatic charge built up in the filter housing will be conducted to thisterminal.

A direct contact between pump and filter media could eliminate such aproblem and the need for a ground wire and its associated failure modes.A direct contact between pump and filter has been proposed in U.S. Pat.No. 5,642,718, which does not address however the problems of the jetpump location/connection.

SUMMARY OF THE INVENTION

The idea behind the present invention is to use a piece of adequategeometry for connecting directly (without any lines extending betweenthem) not only the main fuel supply pump and the fuel filter, but also,the jet pump aimed at filling the reservoir wherein the main pump islocated.

Accordingly, the present invention concerns a fuel system (preferablyfor an automotive engine) comprising a fuel tank, a main fuel supplypump, a fuel filter, a reservoir within the fuel tank and a jet pump forfilling said reservoir, wherein a one piece connector directly connectsthe main fuel supply pump, the fuel filter and the jet pump.

According to the invention, a “one piece” connector may also designate apiece molded in several parts which have been assembled by welding,gluing . . . . However, it preferably is a piece molded in one part, forinstance by injection molding.

This single piece preferably has the form of a “T” into which, in onebranch, the pump is plugged in, the 2 other branches being connected oneto the fuel filter and the other, to the jet pump. This eliminates themultiple components required to create the pressurized line and theindependent passage for operating the jet pump. This typically means atleast 3 less components (fuel line & 2 clamps) and a multiple reductionin failure modes. Additionally it eliminates the negative groundterminal and wire harness for conducting ESD charges.

For practical reasons, the one piece connecting part will be designatedby “T” connection further on, but it is worth noting that the presentinvention covers also other geometries.

This “T” connection is preferably a plastic part, which can be moldedof—or comprise at least in surface (preferably both on its internal andexternal surfaces)—a conductive plastic for EDS (Electro-StaticDischarge) requirements. The preferred plastic is a polyacetal and mostpreferably, POM (polyoxymethelene) which is stable in fuels. It can bemade conductive by adding conductive charges into it (like carbon blackor carbon fibers).

Conductivity requirements mainly depend on the customers' needs and mayextend to the filter parts, which generally at least comprise a housing(generally molded in 2 pieces—a bottom (lower part) and a cover (upperpart)—which are generally welded) and a filter media/element. In somecases, the cover of the filter may be molded as one part with the coverof the reservoir, which eases mounting, saving one part.

Accordingly, there are mainly 3 cases:

-   -   No conductivity required. Basic non-conductive plastic housing,        filter media and “T” connection    -   Partial conductivity. This will require only a conductive filter        element pressed into the lower filter housing molded with        conductive plastic as well, the upper filter housing being of        non conductive plastic. The “T”, molded of conductive plastic,        has an integral molded frame that will press around the grounded        pump shell to complete the path to the negative pump terminal.    -   Full conductivity. Some customers require the entire fuel flow        path from the grounded pump shell to the molded tube in the        flange extending from the fuel filter cover or from the        reservoir cover (the case being) to the fuel line to the engine.        In this case, the upper filter housing will also be molded with        conductive plastic along with the conductive fuel tube connected        to the flange.

Accordingly, a “T” connection made of conductive material is generallyused in combination with at least the lower filter housing and thefilter element being conductive as well, so that charges built up in thefilter can be grounded to the pump through said connection.

As already evoked above, the reservoir according to the invention may beprovided with a cover. According to a preferred embodiment, this coveris molded in one piece with the filter cover, said integrated coverbeing—at least on its surface—of conductive material in the case of fullconductivity solutions.

In a preferred embodiment, said “T” connection directly integrates thejet pump, i.e. a venture tube with an orifice through which pressurizedfuel coming out of the main fuel supply pump can create a flow whichsucks fuel from the main fuel tank into a passage in the reservoir forfilling it.

In another preferred embodiment, the venture tube with the orifice isintegrated in the reservoir and the “T” connection plugs in said tube.

And in a last preferred embodiment, half of the venture tube isintegrated to the “T” connection and the other half, to the reservoir.

In all these preferred embodiments, most preferably, a first fill valveis connected on the passage in the reservoir through which the jet pumpsucks. This valve is aimed at filling the reservoir during the veryfirst filling of the fuel tank or when it has run dry. This valve may beof any type, an umbrella valve giving good results however.

According to another preferred embodiment, at least part of the abovementioned “T” connection is molded in one piece with at least part ofthe filter housing, for instance, with the lower part of it.Alternatively or additionally, said filter housing (preferably, thelower part of the filter housing) can also be molded to retain (orintegrate the housing of) a fuel pressure regulator.

BRIEF DESCRIPTION OF THE DRAWINGS

The above described inventive concept is illustrated in a non limitativeway by FIGS. 1 to 5, wherein:

FIG. 1 is a schematic representation of one embodiment according to theinvention;

FIG. 2 shows an assembly of components according to another embodiment;

FIG. 3 shows a transversal cut into said assembly inserted into areservoir;

FIG. 4 shows a longitudinal cut into the same assembly;

FIGS. 5 and 6 show some preferred aspects of the same embodiment;

FIG. 7 shows a schematic diagram of a third embodiment of the presentinvention;

FIGS. 8 to 11 show a last, fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In these figures, identical numbers designate similar or identicalparts.

FIG. 1 illustrates part of a fuel system according to an embodiment ofthe invention, namely: a one piece “T” connector (1) which receives fueldirectly from a fuel pump (2, not pictured) and distributes it to a jetpump (3, not shown) and to a fuel filter (4). Into the latter, theincoming fuel (i.e. the fuel before filtration) is pictured by whitearrows and the outcoming fuel (i.e. the fuel after filtration) ispictured by black arrows. When it leaves the filter, the fuel is routedto the engine (5, not pictured) at a flow rate controlled by a pressureregulator (6) which has a discharge port (7) to a second jet pump (notpictured) for saddle tank applications. There are 2 valves on thissystem: an anti-siphon valve (8) located before the jet pump and a checkvalve (9). The anti-siphon valve (8), (not visible on the figure; onlyits location is indicated) keeps the reservoir from draining out throughthe fuel pump and out the jet orifice. The check valve (9) maintains thefuel pressure when the engine is turned off (this residual pressure isimportant in order to avoid long engine cranking before building up thepressure to inject the fuel for restarting). In this embodiment, the “T”(1) is a separate part into which the mail fuel supply pump (2), the jetpump (3) and the fuel filter (4) are plugged.

In the embodiment according to FIGS. 2 to 6, the “T” (1) is an integralpart of the plastic lower filter housing (4′) and it integrates the jetpump (i.e. it contains the jet orifice) for filling the reservoir. Thelower housing (4′) connects to a filter element (cartridge, not shown)with a press fit. For OEMs that require the entire fuel flow path (whichincludes the jet pump passage) to be conductive for ESD, this lowerhousing including the “T” is molded with conductive plastic. It can bemolded with non-conductive for other OEMs that do not require ESDremoval. The filter element may also be made conductive for ESD removalthrough the lower filter housing for partial or full conductivity pathto the pump shell.

Four molded latches (4′₁) on the profile of the lower filter housingsnap into corresponding slots on the reservoir wall (not shown in thisfigure) to retain the filter. The lower filter housing (4′) also retainsa fuel pressure regulator (6) with a snap fit to other lower filterhousing latches.

The upper filter housing (4″) connects to the filter element and iswelded to the lower filter housing (4′). This piece (4″) can be moldedwith conductive plastic to remove ESD. It integrates a fuel outlet tube(5′) which connects to a plastic hose to deliver fuel to the enginethough a remote flange (not shown).

A fuel pump (2) plugs into an extension of the “T” (1). This pump (2) iscontained in a shell grounded to the negative pump terminal. The “T” (1)holds a rubber seal (not shown) that secures the fuel pump attachment.The “T” (1) will have a molded frame on the conductive versions whichwill contact the pump shell to complete the required ground path to thenegative terminal.

FIG. 3 shows all these parts assembled/mounted inside a fuel reservoir(10). For this mounting, first, the pump is pressed into the pump shell.This shell has extensions molded on each side which slide intocorresponding slots on reservoir wall not shown). Then, 2 molded disks(1′) on the “T” are pressed into a corresponding molded feature in thereservoir floor which creates the required seal.

The jet pump orifice (3) is integrated in the lower part of the “T” andthrough this orifice, a flow a fuel is created which sucks fuel in thefuel tank outside the reservoir (10) through an opening (11) in saidreservoir, so creating a fuel flow constantly filling the reservoir withfuel from the tank (pictured by white arrows).

FIG. 4 shows how both the pressure regulator (6) and the “T” (1) aremolded integrally with the filter (4), resulting in multiple functionsin a condensed assembly of lower cost.

FIG. 5 completes in fact FIG. 2 and shows how a molded extension of thepump holder (13, not shown in FIG. 2) clips to the “T” (1) to completethe grounding path back to the negative terminal of the fuel pump (2).This eliminates the need for a ground wire.

FIG. 6 shows the same parts, but disassembled (exploded view). To switchto the assembly of FIG. 5, the pump (2) is internally grounded to thepump shell which is then pressed into the pump holder (13). The entireassembly is then plugged into the “T” (1) by means of a rubber seal(13′).

FIG. 7 illustrates another embodiment according to which the reservoircover (12) is molded integrally with the upper filter housing.

Finally, FIGS. 8 to 11 show a fourth embodiment, according to which thejet pump (3) sucks through a first fill valve (14), which is anintegrally molded disc valve according to a co-pending application. Thevalve pictured comprises:

-   -   A piece of material (17, called a disk, although it might be in        the shape of a square) with a hole in it, preferably in its        center.    -   A post that fits through the hole in the disk.    -   Several holes through the reservoir's bottom which are        positioned around the post and in a way such that the disk        covers them when positioned with the post inside its central        hole and when is in its relief position (no pressure lifting the        disk).

FIG. 8 shows how the pump (2) discharges into the “T” (1) a fuel flowwhich is split into a flow to the fuel filter (4) and a flow to a jetpump orifice integrated in a housing (15). The fuel exits the fuelfilter (4) through a pressure regulator (6) which routes the requiredamount of fuel to an engine (5, not pictured) and returns the rest tothe reservoir. The jet pump integrated in the cover (15) sucks fuel fromthe fuel tank through the first fill valve (14, not pictured) and amixing tube (16) discharges into the reservoir, a mixed flow of fuelcoming from the pump (2) on one side (through the “T” (1) and the jetpump) and from the fuel tank (though the first fill valve) on the otherside.

FIG. 9 shows the same assembly but viewed from underneath to illustratehow a small jet orifice (3) blows right into the mixing tube (16),entraining from the fuel tank.

FIG. 10 shows the bottom of the reservoir wherein the system of FIGS. 8and 9 is intended to be mounted. This bottom comprises an integrallymolded disk valve surrounded by a perimeter wall (18). This valvecomprises a rubber disk (17) which:

-   -   is opened by fuel being drawn into the holes of the bottom of        the reservoir (not shown) by the jet flow; and    -   which seals said holes when the jet flow stops to retain        reservoir capacity.

This valve eliminates the need for the check valve in the pump outlet toprevent fuel from siphoning out of the reservoir.

The housing (15) integrating the jet pump presses into the perimeterwall (18) of the reservoir bottom to function as a partial seal to allowthe jet flow to draw fuel through the floor of the reservoir rather thanrecirculation of the fuel inside the reservoir.

FIG. 11 show a longitudinal cut into the system assembled in thereservoir and shows the holes (19) into the bottom of it, holes throughwhich fuel can be sucked from the fuel tank where the reservoir islocated (not shown).

1. A fuel system comprising a fuel tank, a main fuel supply pump, a fuelfilter comprising a housing and a filter element, a reservoir within thefuel tank and a jet pump for filling said reservoir, wherein a one piececonnector directly connects the main fuel supply pump, the fuel filterand the jet pump such that said one piece connector directly contactssaid main fuel supply pump, said fuel filter and said jet pump, and suchthat said fuel system is free of any fuel line between said main fuelsupply pump, said fuel filter and said jet pump.
 2. The fuel systemaccording to claim 1, wherein the one piece connector has the form of a“T” having 3 branches into which, in one branch, the pump is plugged in,the 2 other branches being connected one to the fuel filter and theother, to the jet pump.
 3. The fuel system according to claim 1, whereinthe one piece connector is made of plastic material.
 4. The fuel systemaccording to claim 3, wherein the one piece connector comprisesconductive plastic material at least on its surface.
 5. The fuel systemaccording to claim 4, wherein the filter housing is in 2 parts (oneupper and one lower part) and wherein the lower filter housing and thefilter element comprising conductive material at least on their surface.6. The fuel system according to claim 1, wherein both the filter and thereservoir have a cover and wherein both covers are molded in one piece.7. The fuel system according to claim 1, wherein the jet pump comprisesa venturi tube with an orifice through which pressurized fuel coming outof the main fuel supply pump can create a flow which sucks fuel from themain fuel tank into a passage in the reservoir, said venturi tube beingintegrated either to the one piece connector, to the reservoir or toboth.
 8. The fuel system according to claim 7, wherein a first fillvalve is connected on the passage in the reservoir through which the jetpump sucks.
 9. The fuel system according to claim 1, wherein the onepiece connector is molded in one piece with at least part of the filterhousing.
 10. The fuel system according to claim 1, wherein the filterhousing is molded to retain a fuel pressure regulator.
 11. The fuelsystem according to claim 1, wherein said one piece connector has atleast one conductive surface such that said fuel filter, said main fuelsupply pump and said jet pump are electrically connected to each othervia said one piece connector.
 12. The fuel system according to claim 11,said fuel system being free of any electrical wire between said fuelfilter and ground.
 13. The fuel system according to claim 1, whereinsaid one piece connector is an integral part of said fuel filter. 14.The fuel system according to claim 13, wherein said one piece connectorintegrates the jet pump.
 15. The fuel system according to claim 1,wherein said one piece connector is a single piece of plastic extendingfrom said main fuel supply pump to said fuel filter and to said jetpump.
 16. The fuel system according to claim 15, wherein said one piececonnector is a single piece of molded plastic.